Mechanism for winding a tape from a tape cassette onto a rotatable cylinder of a VCR

ABSTRACT

Movable members of a tape guide member for tape loading are disposed in plural numbers on both the upstream side and the downstream side of a tape running path with respect to a rotatable cylinder, or are disposed in plural number on at least either the upstream side or the downstream side. The plurality of movable members are disposed offset from each other in the radial direction of the rotatable cylinder. Tilt guides for converting the tape running direction are disposed between the associated movable members, and fixed to the stationary component side. A guide passage forming member along which the movable members are guided is also fixed to the stationary component side. Guide portions of the guide passage forming member are provided in plural number individually associated with the movable members. The guide portion nearer to the rotatable cylinder is set to always have a larger tilt angle than that of the outer guide portion with the plane of a tape cassette being a reference. The tilt angles of the guide portions are made different from each other between the upstream side and the downstream side, and are set to direct upwardly with respect to the loading direction at least on either one of the upstream side and the downstream side. A tape tension control member is disposed along the associated guide portion for being rotated about a stationary fulcrum upon movement of the movable member of the tape guide member.

BACKGROUND OF THE INVENTION

The present invention relates to a tape loading mechanism for VCRs(Video Cassette Recorders) adapted to withdraw a magnetic tape out of atape cassette for winding it round a cylinder or to put the magnetictape wound round the cylinder back into the tape cassette, and moreparticularly to a tape loading mechanism for VCRs which requires highreliability of operation.

For improved operability, VCRs are provided with tape loading mechanismswhich automatically withdraw a magnetic tape out of a tape cassette forwinding it round a cylinder (called "loading"), or to automatically putthe magnetic tape wound round the cylinder back into the tape cassette(called "unloading"). The tape loading mechanism comprises, for example,a loading motor, a loading ring and a tape guide member. The tape guidemember is composed of a tape guide unit coming into contact with themagnetic tape and a guide base for supporting the tape guide unit. Whenthe loading ring is rotatably driven by the loading motor, the guidebase of the tape guide unit coupled to the loading ring is moved suchthat the magnetic tape is withdrawn out of a tape cassette by the tapeguide unit mounted on the guide base. When the guide base reaches apredetermined position close to the cylinder, it is fixedly held at thatposition. Specifically, two such guide bases are moved round thecylinder in opposite directions. When those two guide bases arepositioned at their predetermined positions, the magnetic tape is in aloaded condition where it is helically wound round the outer peripheralsurface of the cylinder over a range of predetermined angle. In theunloading operation, the two guide bases are moved in directionsopposite to those in the loading operation, so that the magnetic tape istaken up by a reel in the tape cassette.

The tape guide unit, which is mounted on the guide base and comes intocontact with the magnetic tape, comprises a guide roller and a tiltguide. Hereinafter, the guide base located on the upstream side of thecylinder (i.e., on the side where the magnetic tape running in theforward direction begins to contact with the cylinder) will be referredto as an upstream guide base, while the guide base located on thedownstream side of the cylinder will be referred to as a downstreamguide base.

The cylinder is mounted onto the chassis surface on a tilt A tape leadportion for guiding the magnetic tape wound helically round the outerperipheral surface of the cylinder is tilted with respect to the chassissurface such that the inlet side becomes higher than the outlet side.

Under the condition where the upstream guide base has been positioned bya catcher in the predetermined position close to the cylinder, a runningpath of the magnetic tape from the tape cassette to the guide roller onthe upstream guide base is made parallel to the chassis surface. To keepsuch parallel relation, the level of the magnetic tape is restricted bythe guide roller. The tilt guide on the upstream guide base is inclinedin a predetermined direction with respect to the chassis surface. Thetilt guide is so inclined as to gradually descend the running path ofthe magnetic tape. This allows the magnetic tape to be contacted withthe outer peripheral surface of the cylinder without any torsion, afterit has come into contact with the tilt guide. Also, the magnetic tape isguided by the tape lead portion of the cylinder to run along the outerperipheral surface of the cylinder while being held at its lower edgeagainst the tape lead portion without causing under forces.

Under the condition where the downstream guide base has been positionedby a catcher in the predetermined position close to the cylinder, themagnetic tape which has been so guided round the outer peripheralsurface of the cylinder as to descend gradually by the tape leadportion, is converted in the running direction by the tilt guide on thedownstream guide base such that it now ascends without any torsion. Theguide roller on the downstream guide base makes the running path of themagnetic tape at the same level as that on the inlet side and the tapeface vertical to the chassis surface. The magnetic tape is thereby takenup smoothly by the take-up reel in the tape cassette.

The upstream guide base and the downstream guide base are moved alongpredetermined guide paths as the loading rings revolve. In order toprevent damage of the magnetic tape, it is required that an attitude ofthe magnetic tape is kept stable during such movement as well.

If the force exerted on the magnetic tape during the course from startof the loading operation to end thereof is given by only a force actingin the lengthwise direction of the magnetic tape that is attributable tothe force applied for withdrawing the magnetic tape from the tapecassette, the magnetic tape could be withdrawn from the tape cassettewhile keeping the same attitude as originally accommodated in the tapecassette. Under that condition, there occurs no problem such as damageof the magnetic tape.

However, because the tape lead portion of the cylinder is formed to behigher on the inlet side and lower on the outlet side, the attitude ofthe magnetic tape is forced to change during process of the loadingoperation. The magnetic tape first comes into contact with the outerperipheral surface of the cylinder when it is withdrawn out of the tapecassette for loading. Further, the magnetic tape successively comes intocontact with the other tape guide members, causing the magnetic tape tobe modified in its running path and restricted in its level. Theattitude of the magnetic tape is thereby changed.

If the attitude of the magnetic tape is changed during the loadingoperation in that way, the contact state of the magnetic tape againstthe tape guide member and the cylinder is also changed. This may damagethe edge of the magnetic tape. In the case where a change in theattitude of the magnetic tape produces a force on the magnetic tapeacting in the widthwise direction thereof, for example, the edge of themagnetic tape is strongly pressed against a flange portion of the guideroller. Since the magnetic tape has already been withdrawn from the tapecassette at the time of occurrence of such event, the edge of themagnetic tape is abraded and damaged by the flange portion of the guideroller.

Further, if the attitude of the magnetic tape is changed during theloading operation as mentioned above, the loading operation might becompleted with such change left uncorrected. In this case, the magnetictape is so offset to be ridden over the flange portion of the guideroller or the tape lead portion of the cylinder even after the loadingoperation. If the magnetic tape is run under that condition, the edge ofthe magnetic tape would be damaged. In the case where the magnetic tapeis lifted up away from the tape lead portion, a magnetic head may latchthe edge of the magnetic tape during the recording or reproducingoperation.

As will be apparent from the above explanation, the change in theattitude of the magnetic tape is a very important factor in respect of alevel shift of the magnetic tape. It is therefore required to stabilizethe attitude of the magnetic tape by reducing an amount of the levelshift of the magnetic tape as well as smoothing the change of the tapelevel. As an attempt to achieve it, there is reported a paper written byToshihiko Nakajima, et al., "Application of CAD to Development of VTRMechanism System", Proceeding of the 5th Design Automation EngineeringLecture cosponsored by Japan Society of Mechanical Engineers and JapanSociety of Precision Engineering (1987-7-9), pp. 28-30. This paperdiscusses the method of applying CAD (Computer Aided Design) to designof tape loading mechanisms for analyzing the attitude of a magnetic tapefrom the standpoint of a shift amount of the tape level, with a view toreduce the shift amount and smooth the change in the tape level forstabilizing the attitude of the magnetic tape.

In the VCRs which require very high reliability, such as VCRs forbusiness use by way of example, it is important for the purpose ofsurely preventing damage of the magnetic tape that the tape loadingmechanism is designed to make the shift amount of the tape level smallerthan that in VHS-type VCRs for home use.

As explained above, in conventional VCRs, the upstream guide base ispositioned close to the cylinder and the running path of the magnetictape is modified by the tilt guide to direct downwardly such that themagnetic tape advances along the tape lead portion of the cylinder,during the loading operation. The downstream guide base is alsopositioned close to the cylinder to modify the running direction of themagnetic tape which is departed away from the cylinder to directdownwardly such that the magnetic tape ascends.

However, when the running direction of the magnetic tape is modified bythe tilt guide in that way, there occurs a force for urging the magnetictape to move in the axial direction of the tilt guide (i.e., in thewidthwise direction of the magnetic tape). The widthwise movement of themagnetic tape due to such a force is restricted by the guide roller andthe tape lead portion of the cylinder both of which serve to restrictthe tape level. The above force produced by the tilt guide to move themagnetic tape in the widthwise direction thereof depends on such factorsas an inclination of the tilt guide, a winding angle of the magnetictape over the tilt guide, and a running speed of the magnetic tape. Thelarger the values of these factors become, the greater the forceproduced.

On the other hand, because of the difference in height between the inletside and the outlet side of the tape lead portion of the cylinder, thetilt guide is required to make an abrupt conversion in the runningdirection of the magnetic tape. Therefore, the tilt guide is set to havea large inclination. In conventional VHS-type VCRs, since the runningspeed of the magnetic tape is relatively low during the loadingoperation, the aforesaid force tending to move the magnetic tape in thewidthwise direction thereof has not become serious.

However, in those models of VCRs that the magnetic tape runs at arelatively high speed, such as high-vision VCRs and VCRs for businessuse, the force produced by the tilt guide for moving the magnetic tapein the widthwise direction thereof becomes very large during thereproducing step for search, in particular. The contact force of themagnetic tape against the flange portion of the guide roller and thetape lead portion of the cylinder is increased, resulting in a problemthat the edge of the magnetic tape may be damaged.

Further, conventional tape running systems and tape loading mechanismsfor VCR are known as disclosed in JP-U-59-194153 and an article in VIDEOSALON, "Fundamental Knowledge of Video", (1989, Vol. 4, p.40), forexample.

In these magnetic recording and reproducing devices, a cylinder ismounted onto a chassis surface via a cylinder base on a tilt. A tapelead portion is provided on the outer peripheral surface of the cylinderfor guiding the magnetic tape helically wound.

After the magnetic tape has been withdrawn out of a tape cassette, guidebases are positioned in their predetermined positions close to thecylinder by respective catchers provided integrally with the cylinderbase. Under this condition, the running path of the magnetic tape fromthe tape cassette to the guide rollers on the guide bases is keptparallel to the chassis surface. Thus, in order to allow the magnetictape to be contacted with the outer peripheral surface of the cylinderwithout any torsion, the tilt guides are mounted on the guide bases soas to tilt in the predetermined directions with respect to the chassissurface.

In addition, the guide bases are provided with tilt surfaces on whichthe tilt guides are to stand upright, respectively.

As described above, the prior art requires at least three different tiltsurfaces; i.e., the tilt surface of the cylinder base on which thecylinder is to be mounted, the tilt surface of the guide base on theinlet side of the cylinder, and the tilt surface of the guide base onthe outlet side of the cylinder.

In the prior art, therefore, manufacture of parts having those tiltsurfaces has been accompanied by difficulties in point of ensuring therequired part accuracy, and the complexity of part configurations hasalso pushed up the cost.

Particularly, in high-vision VCRs and VCRs for business use, since themagnetic tape is run at a relatively high speed, the various guides arerequired to meet higher accuracy in assembly.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a tape loadingmechanism for the VCR which can surely prevent damage of a magnetic tapeeven when it runs at a high speed, make it easier to ensure accuracy ofvarious tape guides, and reduce the cost easily.

To this end, in accordance with the present invention, there areprovided parallel guide passages extending from a part of a tapecassette to the upstream and downstream sides of a cylinder,respectively and being substantially parallel to the chassis surface,and tilt guide passages extending from a part of the tape cassette tothe upstream and downstream sides of the cylinder, respectively andbeing tilted in at least a part thereof with respect to the chassissurface. These parallel guide passages and the tilt guide passages serveas guide passages for separate guide rollers, respectively. Tilt guidesare fixedly provided to be located between two guide rollers which havebeen guided to the upstream and downstream sides of the cylinder,respectively.

In the present invention, the guide rollers movable along the guidepassages arranged on the outer side with respect to the cylinder aremade to move preceding the guide rollers movable along the guidepassages arranged disposed inner than the outer side guide passages.

Further, the present invention includes a pinch roller drive motorseparately from a loading motor and from a capstan roller. The pinchroller drive motor swings a pinch roller arm integrally mounted on aworm wheel through a worm and the worm wheel.

The tilt guides and the tilt surfaces for running and loading themagnetic tape are all integrally incorporated into a cylinder base usedfor mounting the cylinder onto the chassis on a tilt, thereby achievingthe above object.

In the present invention, also included is a mechanism for detectingtape tension of the magnetic tape on running. This mechanism iscooperated with the loading and unloading operation of the magnetictape. Under an unloading operation, the tension detecting mechanism isstored back into the tape cassette.

Since each guide roller is moved along the guide passages independentfrom each other, the attitude and timing of the guide rollers duringtheir movement can be set independently, and the shift amount of thetape level during the loading operation can hence be restrained to bevery small. Also, since the tilt guides are located sufficiently awayfrom the cylinder, tilt angles of the tilt guides and the tape windingangles over the tilt guides are made smaller, thereby allowing themagnetic tape to come into contact with the cylinder very smoothly andalso to be departed away from the cylinder smoothly. Therefore, evenwhen the magnetic tape is run at a high speed, the force in thewidthwise direction of the magnetic tape produced by the tilt guidesbecomes small.

Further, by moving the guide rollers movable along the guide passagesarranged on the outer side ahead of the guide rollers movable along theguide passages arranged on the inner side, the magnetic tape iswithdrawn out of the tape cassette substantially parallel thereto,whereby the magnetic tape is smoothly withdrawn and the loadingoperation is stabilized.

Moreover, while the pinch roller arm is swung by the pinch roller drivemotor, the pinch roller and the capstan remain in a contact state evenafter the pinch roller drive motor is deenergized, because of aself-lock between the worm and the worm wheel, once the pinch roller andthe capstan are contacted with each other.

In addition, all of the tilt surfaces, which have presented difficultiesin manufacture, are incorporated into the cylinder base serving as areference for positional accuracy of the tape running system. Therefore,the positional relationship between the cylinder and the tilt guides isnot based on assemblying accuracy of the chassis and other intermediatecomponents, but on manufacturing accuracy of the cylinder base, therebyresulting in higher accuracy. Also, since in the present invention,additional tilt surfaces of the remaining components other than thecylinder base are incorporated into the cylinder base which hasoriginally complicated shape including the intrinsic tilt surfaces,these components are simplified and then the cost is reduced.

Moreover, since the tape tension detecting mechanism is operated duringtape running to issue a signal for detecting the tape tension, a reelmotor can be controlled using the signal to improve accuracy of the taperunning performance, whereby a reproduction signal obtained from amagnetic head provided on the rotatably cylinder is also improved inquality, while surely preventing damage of the magnetic tape running.

In addition, the tape tension detecting mechanism is stored back intothe tape cassette under an unloading operation, and there occurs notrouble in loading of the tape cassette. That mechanism is brought intocontact with the non-magnetic surface of the magnetic tape, so that themagnetic surface of the magnetic tape will not be damaged.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a tape loading mechanism for a VCR according toone embodiment of the present invention in an unloaded condition where amagnetic tape is put back in a tape cassette;

FIG. 2 is a plan view showing the mechanism in a completely loadedcondition where the magnetic tape is wound round a cylinder;

FIG. 3 is a perspective view showing the mechanism shown in FIG. 2;

FIG. 4 is a plan view showing a tape running path in the embodiment;

FIG. 5 is an illustration showing a tape loading process in theembodiment;

FIG. 6 is a perspective view showing the tape loading process based onCAD (Computer Aided Design) in three dimensions;

FIG. 7 is an illustration showing the result calculated by a loadingsimulator on shift amounts of a tape level during the tape loadingprocess;

FIG. 8 is a plan view showing various guides in detail;

FIG. 9 is a perspective view showing the guides shown in FIG. 8;

FIG. 10 is a perspective view showing components of the cylinder base;

FIG. 11 is a plan view showing a detailed contact state of guide basesshown in FIG. 2;

FIG. 12 is a perspective view showing a part the guide bases shown inFIG. 11;

FIG. 13A is a side view showing a tape tension detecting mechanism;

FIG. 13B is a plan view showing the detecting mechanism shown in FIG.13A; and

FIG. 14 is a partially sectional view showing a reel base mechanismshown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, an embodiment of the present invention will be describedwith reference to accompanying drawings.

Referring to FIGS. 1 to 3, a reference numeral 1 designates a cylinderbase on which a cylinder 6 is mounted on a tilt by a predetermined anglewith respect to a chassis 7. The element designated at a referencenumeral 12 is a magnetic tape; 8 and 9 are guide rollers as upper limitguides; 10 and 11 are guide rollers; 13 and 14 are tilt guides; 15 and16 are impedance rollers; 17 is a guide roller as a lower limit guide;18 is an AC (audio and control) head; 19 is a pinch roller; 20 is acapstan; 21 is a tension roller; 22 is a guide plate; 23 to 26 are guideslits; 27 and 28 are loading rings; 29 to 32 are catchers; 33 is aloading motor; 34 is a capstan motor; 35 to 38 are guide bases; 39 is atension lever 40 is a pinch roller arm; 41 is a drive pin; 42 is a wormwheel; 43 is a pinch roller drive motor; 44 is a tape cassette; 45 is anopening; 46 is a supply reel; 47 is a take-up reel; 48 is a supply reelbase; 49 is a take-up reel base; 50 is a base for positioning the tapecassette; and 51 is a slack sensor roller.

The guide plate 22 is provided with the horizontal guide slits 23 to 26,and it is attached at one end thereof to the chassis 7 and at the otherend thereof to the cylinder base 1. A part of the one end of the guideplate 22 is located in the opening 45 of the tape cassette 44. The guideslits 23, 24 extend near from the opening 45 of the tape cassette 44 tothe guide slits 52, 53 formed in the cylinder base 1, respectively. Theyterminate at the upstream side of the cylinder 6. The guide slits 24 and53 are located closer to the cylinder 6 than the guide slits 23 and 52.In particular, the guide slit 53 is located very close to the cylinder6. The guide slits 52 to 55 are shown in detail in FIG. 10. At the endsof the guide slits 52 and 53 on the upstream side of the cylinder 6,plate-like catchers 29 and 30 each having a V-shaped groove are mountedto the cylinder base 1. The guide base 35 mounting thereon the guideroller 10 and the guide base 36 mounting thereon the guide roller 8 asthe upper limit guide are movably fitted in and among the guide slits 23and 52, and 24 and 53. The guide bases 35 and 36 are to be located inthe opening 45 of the tape cassette when they are at one end of theirrespective guide slits 23 and 24, as shown in FIG. 1, and are to bepositioned by the respective catchers 29 and 30 at the ends of the guideslits 52 and 53, as shown in FIG. 2.

Likewise, the guide slits 25 and 26 also extend from near from theopening 45 of the tape cassette 44 to the guide slits 54 and 55 formedin the cylinder base 1, respectively. They terminate at the downstreamside of the cylinder 6. The guide slits 25 and 54 are located closer tothe cylinder 6 than the guide slits 23 and 52. In particular, the guideslit 54 is located very close to the cylinder 6. At the ends of theguide slits 54 and 55 on the downstream side of the cylinder 6,plate-like catchers 31, 32 each having V-shaped groove are mounted tothe cylinder base 1. The guide base 38 mounting thereon the guide roller11 and the guide base 37 mounting thereon the guide roller 9 as theupper limit guide are movably fitted in and along the guide slits 26 and55, and 25 and 54. The guide bases 37 and 38 are to be located in theopening 45 of the tape cassette when they are at one end of theirrespective guide slits 25 and 26, as shown in FIG. 1, and are to bepositioned by the respective catchers 31 and 32 at the ends of the guideslits 54 and 55, as shown in FIG. 2.

The guide plate 22 is parallel to the chassis 7 and has no tiltsurfaces. Therefore, all of the guide slits 23 to 26 lie horizontally.The guide slits 52 and 55 formed in the cylinder base 1 also extendhorizontally parallel to the chassis 7.

Referring to FIGS. 8 to 10, a tilt surface 56 is formed such that thecylinder 6 has a tilt angle of 5.75° and the tilting direction ofθ=180°. The θ is given by an angle measured counterclockwise from the Xaxis of the coordinates which are defined in the plan view of FIG. 8such that the origin O is the center of the cylinder and a lineconnecting the centers of the supply reel base and the take-up reel baseis the X axis.

Meanwhile, the part of the cylinder base 1 in which the guide slit 53 isprovided is inclined by an inlet side first tilt surface 2 at an angleof 3.54° with respect to the surface of the chassis 7. Then, an inletside second tilt surface 3 is inclined at an angle of 8.28° with respectto the surface of the chassis 7. This tilt angle of 8.28° is equal to anangle at which the guide roller 8 is to be inclined. The inlet sidefirst tilt surface 2 and the inlet side second tilt surface 3 are set tohave the tilting direction of θ=210.81°. This tilt direction angleθ=210.81° is equal to a tilt direction angle at which the guide roller 8is to be inclined.

Likewise, a part of the cylinder base 1 in which the guide slit 54 isprovided is inclined downwardly by an outlet side first tilt surface 4at an angle of 4.41° with respect to the surface of the chassis 7. Then,an outlet side second tilt surface 5 is inclined at an angle of 7.99°with respect to the surface of the chassis 7. The outlet side first tiltsurface 4 and the outlet side second tilt surface 5 are set to have thetilting direction of θ=151.1°. This tilt direction angle θ=151.1° isequal to a tilt direction at which the guide roller 9 is to be inclined.

Since the guide slits 23 to 26 and 52 to 55 thus formed, when the guidebases 35 to 38 are moved from the tape cassette 44, the guide bases 35,38 are moved parallel to the chassis 7 along the guide slits 23 and 52,and 26 and 55, respectively. But, the guide base 36 is first movedparallel to the chassis 7 and then directed upwardly, while the guidebases 35, 36, 37 and 38 reach their stop positions defined by thecatchers 29, 30, 31 and 32, respectively.

Construction of other guides will now be described. FIG. 9 shows acondition that the guide bases 35, 36, 37 and 38 are positioned by thecatchers 29, 30, 31 and 32, respectively. The tilt guide 13 and theimpedance roller 15 are mounted on the cylinder base 1 so as to belocated between the guide rollers 10 and 8 under this condition. On thedownstream side of the cylinder base 1, the guide roller 17, the AC head18 and the tilt guide 14 are mounted on the cylinder base 1 so as to belocated between the guide rollers 9 and 11. Here, the running path ofthe magnetic tape 12 is defined such that the tilting direction and thetilt angle of the impedance roller 15 become equal to those of the guideroller 8, and the tilting directions and the tilt angles of the guideroller 17 and the AC head 18 become equal to those of the guide roller9, respectively. Therefore, the inlet side second tilt surface 3 isformed to spread over a wide area including the vicinity of the guideslit 53, permitting the impedance roller 15 to be erected on the inletside second tilt surface 3. Further, the mounting area of the guideroller 8 and surroundings thereof, the mounting area of the impedanceroller 15 and surroundings thereof, as well as a catcher surface 57 havethe same tilt angle and the tilting direction as those of the inlet sidesecond tilt surface 3. Accordingly, the above parts can be machinedsimultaneously with the cylinder base 1 so that dimensional accuracy ofthose parts in the tape running system can be improved easily. It is tobe noted that an impedance roller base 60 is not only mounted in such amanner as allowing adjustment of a level of the impedance roller 15 witha lower limit flange by means of a screw, but also screwed at threepoints to the cylinder base 1 through respective springs so that thetilt angle and the tilting direction of the impedance roller base 60 maybe finely adjusted dependent on actual tape running conditions.

The tilt guide 13 is fixed to a tilt guide base 59 and then integrallyassembled to the horizontal surface of the cylinder base 1 by means ofscrews or the like. Thus, the tilt guide base 59 is a part which has atilt surface (of a tilt angle of 14.85° and a tilting directionθ=284.96°). However, by inserting a spacer between the tilt guide base59 and the cylinder base 1 on assembling, the tilt guide base 59 can beassembled with high accuracy while measuring actual accuracy of the tiltguide 13.

On the other hand, the outlet side second tilt surface 5 is formed tospread over a wide area including not only the vicinity of the guideslit 54 but surroundings thereof, permitting the guide roller 17 and theAC head 18 to be erected on the outlet side second tilt surface 5. Aguide roller base 61, a first AC head base 62 and a second AC head base63 are therefore not required to have their specific tilt surfaces.Further, the mounting area of the guide roller 9 and surroundingsthereof, the mounting area of the guide roller 17 and surroundingsthereof, the mounting area of the AC head 18 and surroundings thereof,as well as a catcher surface 58 have the same tilt angle and the tiltingdirection as those of the outlet side second tilt surface 5.Accordingly, the above parts can also be machined simultaneously withthe cylinder base 1 so that dimensional accuracy of those parts in thetape running system can be improved easily. It is to be noted that aguide roller base 61 is not only mounted in such a manner as allowingadjustment of a level of the guide roller 17 with a lower limit flangeby means of a screw or the like, but also assembled integrally to theoutlet side second tilt surface 5 of the cylinder base 1 by means ofscrews or the like. Thus, the guide roller base 61 is a part which hasno tilt surface. By inserting a spacer between the guide roller base 61and the cylinder base 1 on assemblying, the guide roller base 61 can beassembled with high accuracy while measuring actual accuracy of theguide roller 17.

The AC head 18 is fixed onto and upright from the second AC head base63. As shown in FIG. 8, too, the second AC head base 63 is screwed atthree points to the first AC head base 62 through respective springs sothat the Azimuth angle and the tilt angle of the AC head 18 with respectto the magnetic tape 12 may be finely adjusted. The first AC head base62 is swingable on and vertically slidable along a shaft 65.Specifically, though not shown, the first Ac head base 62 is adapted atits end to abut with an adjusting nut 66, and adjusted vertically bymeans of a nut at an upper part of the shaft 65 while being biasedvertically by a spring. The adjusting nut 66 has a conical shape and, asit is moved vertically, permits to finely adjust the phase andpositional relationship between a video signal write-start position onthe magnetic tape 12 and a control signal.

Further, the tilt guide 14 is fixed to a tilt guide base 64 and thenintegrally assembled to the horizontal surface of the cylinder base 1through the base 64 by means of screws or the like. Thus, the tilt guidebase 64 is a part which has a tilt surface (of a tilt angle of 33.95°and a tilting direction θ=67.05°). The tilt guide base 64 permits theassembly of tilt guide 14 with high accuracy.

The other construction of the tape loading mechanism will be describedbelow. On the chassis 7, there are arranged two loading rings 27 and 28capable of revolving round the cylinder 1 (via gearings, though omittedin the figures). These loading rings 27 and 28 are laid one on the otherand can pass below the guide plate 22, and the inlet side first tiltsurface 2, the inlet side second tilt surface 3, the outlet side firsttilt surface 4 and the outlet side second tilt surface 5 of the cylinderbase 1. The loading rings 27 and 28 are coupled via gearings to theloading motor 33 mounted on the chassis 7 so as to revolve in oppositedirections. The revolution of the loading ring 27 moves the guide bases35 and 36, while the revolution of the loading ring 28 moves the guidebases 37 and 38. In construction of this embodiment, a revolution angleof the loading ring 27 about the center of revolution is set to beapproximately 108° clockwise, and a revolution angle of the loading ring28 is set to be approximately 120° counterclockwise. A small magnet issecured to the lower surface of the loading ring 28, while a sensorsubstrate 67 having a sensor, such as a Hall element, is secured to thechassis 7. The sensor detects the small magnet to determine the timingat which the loading rings 27 and 28 are to be stopped.

On a side of the supply reel 46 of the tape cassette 44, the tensionlever 39 is pivotable on a shaft 69 on a tension plate 68. The tensionroller 21 is rotatably mounted to the distal end of the tension lever39. The rollers 74 and 75 are rotatably mounted to the guide plate 22and arranged such that the tension roller 21 is adapted to be positionedtherebetween.

On a side of the take-up reel 49 of the tape cassette 44, the worm wheel42 is disposed to be driven by the pinch roller drive motor 43 forrotation, and the pinch roller arm 40 is supported by a bearing 70provided on the shaft to which the worm wheel 42 is mounted. A drive pin41 planted on the pinch roller arm 40 is engaged with the worm wheel 42through a torsion spring. The pinch roller 19 is rotatably supported onthe distal end of the pinch roller arm 40. When the pinch roller drivemotor 43 is driven to make the pinch roller arm 40 pivot clockwise onthe bearing 70, the pinch roller 19 is tightly contacted with thecapstan 20.

The slack sensor roller 51 is born rotatably with respect to a sensorarm 71. The sensor arm 71 is normally biased counterclockwise by aspring and rotatably engaged with a sensor plate 73 fixed at a bearing72 to the chassis 7.

A full-width eraser head 76 and the impedance roller 16 are mounted tothe guide plate 22 through a base.

The positioning base 50 is fixed to the chassis 7 by pins 79 and 80. Thepositioning base 50 is engaged with the tape cassette 44 through pins 77and 78 for properly positioning the tape cassette 44.

Next, operation of this embodiment will be described.

There will first be explained an unloaded condition where the tapecassette 44 is just fitted. The supply reel 46 of the tape cassette 44is rested on the supply reel base 48 rotatably mounted on the chassis 7,while the take-up reel 47 is rested on the take-up reel base 49. Themagnetic tape 12 is stretched between the supply reel 46 and the take-upreel 47 within the tape cassette 44. The guide rollers 10, 8, 9 and 11on the guide bases 35, 36, 37 and 38, the tension roller 21 on thetension lever 39, and the pinch roller 19 on the pinch roller arm 40 arelocated in the opening 45 of the tape cassette 44 at inside of themagnetic tape 12.

When the loading operation is started under the above condition, theloading ring 28 is revolved clockwise by the loading motor 33 so thatthe guide bases 37 and 38 are moved along the guide grooves 25 and 54,and 26 and 55, respectively, while the loading ring 27 is revolvedcounterclockwise so that the guide bases 35 and 36 are moved along theguide grooves 23 and 52, and 24 and 53, respectively.

As the loading ring 27 revolves counterclockwise, the tension lever 39is swung counterclockwise. With some time lag, the pinch roller arm 40is swung clockwise by the pinch roller drive motor 43.

Upon movement of the guide bases 35, 36, 37 and 38, the guide rollers10, 8, 9 and 11 mounted thereon are brought into contact with themagnetic tape 12 in the tape cassette 44, to thereby withdraw themagnetic tape 12 out of the tape cassette 44. At this time, the tensionroller 21 and the pinch roller 190 have no contribution to withdraw themagnetic tape 12.

Afterward, the guide bases 35, 36, 37 and 38 reach the respectivecatchers 29, 30, 31 and 32 and then are positioned, thereby the magnetictape 12 is helically wound round the outer peripheral surface of thecylinder 6 over a range of predetermined angle. The loading operation isthus completed. The magnetic tape 12 is wound along a helical tape leadportion on the outer peripheral surface of the cylinder 6.

FIG. 4 shows the running path of the magnetic tape in a loaded conditionthus obtained.

The magnetic tape 12 is led out from the supply reel 46 to be contactedwith the roller 75, the tension roller 21 and the roller 74, andthereafter comes into contact with the full-width eraser head 76.Afterward, the guide roller 10 changes the running direction of themagnetic tape 12 toward the cylinder 6. The tape face of the magnetictape 12 is inclined by the tilted guide 13 according to an inclinationof the cylinder 6, and contacts with the impedance roller 15. After thetape lower edge is restricted by a lower flange of the impedance roller15, the magnetic tape 12 comes into contact with the cylinder 6 via theguide roller 8 as an upper limit guide.

While running round the cylinder 6, the magnetic tap 12 is restricted atits lower edge by the tape lead portion of the cylinder.

On the downstream side of the cylinder 6, the magnetic tape 12 from thecylinder 6 first comes into contact with the guide roller 9 as an upperlimit guide, and then contacts with the guide roller 17 as a lower limitroller and the AC head 18. Afterward, the tilt guide 14 makes the tapeface vertical with respect to the chassis 7, and the guide roller 11changes the running direction of the magnetic tape toward the tapecassette 44. At this time, the guide roller 11 also serves to restrictthe upper edge of the magnetic tape 12. The magnetic tape 12 thuschanged in the running direction contacts with the impedance roller 16while being thereby restricted at its lower edge. Thereafter, themagnetic tape 12 passes between the pinch roller 19 and the capstan 20,comes into contact with the slack sensor roller 51, and is then taken upby the take-up reel 47 of the tape cassette 44.

When the aforesaid tape running path is established and the capstan 20is rotated by the capstan motor 34, the magnetic tape 12 tightlysandwiched between the pinch roller 19 and the capstan 20 is caused torun along the above running path. At this time, the tension roller 21detects back tension of the magnetic tape, and the load corresponding tothe detected result is applied to the supply reel 46 so that the tapetension is controlled to become a predetermined value. On the otherhand, between the capstan 20 and the take-up reel 47, the slack sensorroller 51 determines whether the rotational speed of the take-up reel 47is proper or not, for thereby controlling the take-up rate of themagnetic tape 12.

Referring to FIGS. 11 and 12, under a loaded condition, the guide bases35, 36, 37 and 38 are pressed against and positioned by the respectiveV-shaped engagement portions of the catchers 29, 30, 31 and 32. Theguide base 36 is pressed against a pin 86 planted on a loading lever 92which is moved below the cylinder base 1 upon rotation of the loadingring 27. The pin 86 is fitted in the guide slit 24 of the guide plate22. Thus, as the loading ring 27 rotates, the guide base 36 is movedalong the guide slit 24 and the guide slit 53 formed in the cylinderbase 1. The guide base 35 is also moved in a like manner to the guidebase 36. Under a loaded condition, the guide roller 10 is set verticalwith respect to the chassis 7, but the guide roller 8 is inclined withrespect to the chassis 7.

The guide slit 53 of the inlet side second tilt surface 3 shown in FIG.10 is set to have such a length that the guide base 36 is in its fullsize located to just occupy the whole guide slit 53 under a loadedcondition. Meanwhile, the inlet side first tilt surface 2 is formed soas not to damage the edge of the magnetic tape 12 due to an abruptchange in the attitude of the guide base 36 during the loading process.However, it is not necessary to subdivide the configuration of the guideslit 53 into still narrower tilt surfaces or more intricate curves. Thereasons are in that there exists no substantial difference in themovement path of the guide base 36 dependent on the modifiedconfigurations of the guide slit 53, that the cylinder base 1 canotherwise be manufactured easily, and that the larger overall length ofthe guide base 36 is advantageous in improving the positioning accuracy.

The foregoing also equally applies to the guide bases 37 and 38 on thedownstream side of the cylinder 6.

In FIGS. 11 and 12, the element designated at a reference numeral 81 isa loading holder; 95 and 96 are support shafts; 92 is a loading lever;91 is an upper loading lever; 99 is a lower loading lever; 85 and 86 arepins; 83 is a tension spring; and 89 is a compression spring.

A loading holder 81 is engaged with the loading ring 27 in such a mannerthat the loading holder 81 can be moved over a predetermined distance(e.g., about 3 mm) in the lengthwise direction thereof.

The tension spring 83 is disposed between the distal end of the loadingholder 81 and the loading ring 27. The loading holder 81 is biased bythe tension spring 83 on the loading ring 27 in the same direction(clockwise in the figure) of rotation thereof during the loadingoperation.

The loading holder 81 has two support shafts 95 and 96 planted thereon,to which the lower loading lever 99 and the loading lever 92 arepivotaly mounted, respectively. The loading lever 92 has the pin 86planted thereon, with which the guide base 36 is engaged. On the otherhand, the upper loading lever 91 is slidably attached to the lowerloading lever 99 so as to produce compression reaction, which is biasedinto a stretched state by the spring 89. The upper loading lever 91 hasat its distal end the pin 85 planted thereon, with which the guide base35 is engaged. The pin 85 is fitted in the guide slit 23 of the guideplate 22 and the guide slit 52 of the cylinder base 1.

When the loading ring 27 is revolved upon start of the loadingoperation, the loading holder 81 lying on the loading ring 27 is alsomoved while being biased by the tension spring 83, whereupon the guidebase 35 and 36 are moved along the guide slit 23 and 52, and 24 and 53while being pushed by the loading lever 92 and the upper and lowerloading levers 91 and 99, respectively. The guide base 35 is firstfitted into the V-shaped engagement portion of the catcher 29, but theloading ring 27 further continues to revolve. As a result, thecompression spring 89 is compressed so that the guide base 35 comes intopress contact with the catcher 29. The guide base 36 is then fitted intothe V-shaped engagement portion of the catcher 30. The loading ring 27is further moved through about 3 mm and then stopped. Once the guiderollers 10 and 8 are brought into contact with the catchers 29 and 30,respectively, the loading holder 81 can no longer move. But, only theloading ring 27 is thereafter moved through the above distance so thatthe tension spring 83 is stretched. The increased biasing force of thetension spring 83 thus stretched causes the guide rollers 10 and 8 tocome into press contact with the catchers 29, 30, respectively, therebyfixing their attitudes. At this time, the guide bases 35 and 36 undergothe moment incidental to the above press contact via the pins 85 and 86with the V-shaped grooves of the catchers 29 and 30 serving as fulcra,respectively. The distal ends of the guide bases 35 and 36 are therebybrought into press contact with the lower surface of the cylinder base 1in the same areas as where the catchers 29 and 30 are fixed to the uppersurface of the cylinder base 1.

Meanwhile, on the downstream side of the tape running path with respect,to the cylinder 6, the element designated at guide roller 9 by referencenumeral 82 is an upper loading holder; 101 is a lower loading holder; 97and 98 are support shafts; 93 is a loading lever; 94 is an upper loadinglever; 100 is a lower loading lever; 87 and 88 are pins; 84 is a tensionspring and 90 is a compression spring.

As shown in FIGS. 11 and 12, the difference between the downstreamloading mechanism and the upstream loading mechanism along the taperunning path resides only in that the upper loading holder 82 is fixedto the lower loading holder 101 and similarly engaged with the loadingring 28 through the lower loading holder 101 on the downstream side. Thedetailed description of the downstream loading mechanism is thereforeomitted.

In FIGS. 11 and 12, since the loading holders 81, 82 and 101 are movablewith respect to the loading rings 27 and 28 through the tension springs83 and 84, respectively, the difference in strokes until establishmentof the aforesaid press contact of the guide rollers between the upstreamand downstream sides can be absorbed. Also, since the upper loadinglever 91 and the lower loading lever 99 are movable with respect to theloading lever 92 through the compression spring 89, it becomes possibleto absorb the difference in strokes until establishment of the presscontact of the guide rollers 10 and 8 due to such factors as dimensionalerrors of the respective levers. Likewise, since the upper loading lever94 and the lower loading lever 100 are movable with respect to theloading lever 93 through the compression spring 90, it becomes possibleto absorb the difference in strokes until establishment of the presscontact of the guide rollers 9 and 11.

FIG. 4 shows the tape running path in a loaded condition thus obtained.The components shown in FIG. 4 corresponding to those in FIGS. 1 to 3are designated by the same reference numerals.

In FIG. 4, the magnetic tape 12 is led out from the supply reel 46 to becontacted with the roller 75, the tension roller 21 and the roller 74,and then comes into contact with the full-width eraser head 76.Afterward, the guide roller 10 changes the running direction of themagnetic tape toward the cylinder 6. The magnetic tape 12 thus changedin the running direction is inclined in its tape face by the tilt guide13 according to an inclination of the cylinder 6, and contacts with theimpedance roller 15. Thereafter, the magnetic tape comes into contactwith the cylinder 6 through the guide roller 8.

On the downstream side with respect to the cylinder 6, the magnetic tape12 from the cylinder 6 first comes into contact with the guide roller 9,and then contacts with the guide roller 17 and the AC (audio andcontrol) head 18. Afterward, the tilt guide 14 makes the tape facevertical with respect to the chassis 7 (FIG. 1), and the guide roller 11changes the running direction of the magnetic tape toward the tapecassette 44. The magnetic tape 12 thus changed in the running directioncontacts with the impedance roller 16, and passes between the pinchroller 19 and the capstan 20 and then comes into contact with the slacksensor roller 51 for being taken up by the take-up reel 47 of the tapecassette 44.

Thus, the tape running path is established and the magnetic tape 12 istightly sandwiched between the pinch roller 19 and the capstan 20. Whenthe capstan 20 is rotated by the capstan motor 34 under such condition,the magnetic tape 12 runs along the above running path. At this time,the tension roller 21 detects tension of the magnetic tape. The loadcorresponding to the detected value of tape tension is applied to thesupply reel 46 so that the tape tension value is held at a predeterminedconstant value.

The tilt guide 13 is inclined with respect to the surface of the chassis7 (hereinafter referred to as chassis surface), whereby the running pathof the magnetic tape 12 is changed from the direction parallel to thechassis surface until the guide roller 10 to the upward direction. Themagnetic tape 12 thus changed in the running direction is contacted withthe impedance roller 15 and then again changed in the running directionby the guide roller 8 so as to now gradually is, thereby coming intocontact with the outer peripheral surface of the cylinder 6. Whilerunning round the outer peripheral surface of the cylinder 6, themagnetic tape 12 is kept at its lower edge smoothly contacted with thetape lead portion of the cylinder 6 without causing undue forces.

In order to run the magnetic tape 12 on the upstream side with respectto the cylinder 6 as mentioned above, the level and the runningdirection of the magnetic tape 12 are restricted by the guide roller 8between the guide roller 8 and the tape lead portion of the cylinder 6such that the lower edge of the magnetic tape 12 lies on an extension ofthe tape lead portion.

Further, the guide roller 8 is inclined with respect to the chassissurface so as to change the tape running direction directed upwardlyfrom the tilt guide 13 to the downward direction parallel to the tapelead portion as stated above. Specifically, when the upstream guide base36 is positioned by the catcher 30, the attitude of the guide roller 8is thereby set such that it is erect perpendicularly to the planeincluding the ascending tape running path and the descending taperunning path in front and rear of the guide roller 8. This permits theguide roller 8 to change the tape running direction as mentioned above,while not causing any force acting on the magnetic tape 12 in thewidthwise direction thereof. The guide roller 8 is positioned close tothe cylinder 6, while the tilt guide 13 is located sufficiently awayfrom the cylinder 6 and disposed between the guide roller 10 and theguide roller 8. Therefore, the tilt guide 13 and the guide roller 8 aresufficiently remote from each other, so that an ascending slope of thetape running path due to the tilt guide 13 becomes small and the runningdirection change other than an ascent of the magnetic tape is notrequired. This makes it possible to set the tilt angle of the tilt guide13 small and also the tape winding angle over the tilt guide 13 small.As a result, the force offered by the tilt guide 13 and acting on themagnetic tape 12 in the widthwise direction thereof becomes very small.

The above explanation is also equally applicable to the downstream sideof the cylinder 6. Specifically, when the downstream guide base 37 ispositioned by the catcher 31 close to the cylinder 6, the magnetic tape12 departing downwardly from the cylinder 6 is caused by the guideroller 9 to now run upwardly. To this end, the attitude of the guideroller 9 is set such that it is erect perpendicularly to the planeincluding both the tape running paths in front and rear of the guideroller 9. This allows the guide roller 9 not to cause any force actingon the magnetic tape 12 in the widthwise direction thereof. Also, themagnetic tape 12 running upwardly from the guide roller 9 is changed inits running direction by the tilt guide 14 so that it now runs parallelto the chassis surface. Simultaneously, the level of the magnetic tape12 running parallel to the chassis surface is made equal to the level ofthe magnetic tape 12 on the upstream side of the cylinder 6. This levelrestriction is performed by the guide roller 11. Here, the distancebetween the guide roller 9 and the tilt guide 14, through which themagnetic tape 12 is run upwardly, is sufficiently long. Therefore, it ispossible to set sufficiently small an ascending slope at which themagnetic tape runs upwardly. Thus, the tilt angle of the tilt guide 14necessary for changing the ascending running direction of the magnetictape 12 to the parallel direction with respect to the chassis surfacebecomes very small. Also, any change in the tape running direction otherthan the above direction change is not required, and the tape windingangle over the tilt guide 14 can also be made sufficiently small. As aresult, the force produced by the tilt guide 14 and acting on themagnetic tape 12 in the widthwise direction thereof becomes very small.

In conventional VCRs, because the tilt guides are positioned close tothe cylinder and the running direction of the magnetic tape is largelychanged so as to follow the tape lead portion of the cylinder, it hasbeen required to set both the tilt angles of the tilt guides and thetape winding angles over the tilt guides large. In this embodiment,however, not only the tilt angles of the tilt guides but also the tapewinding angles over the tilt guides can be set small. This also makesthe force offered by the tilt guides for pushing the tape up or downsmall. Accordingly, the force pressing the tape edge against the guiderollers and the tape lead portion of the cylinder becomes so small thatthe magnetic tape can be protected from damage.

Next, the tape loading process will be described. In the tape loadingmechanism, as mentioned above, there arise such problems due to theattitude of the magnetic tape during the tape loading process as damageof the tape edge, lift-up of the magnetic tape at various tape guidemembers, and slack of the magnetic tape. If the magnetic tape iswithdrawn out of the tape cassette parallel to the chassis surface andthen brought into contact with an outer peripheral surface vertical tothe chassis surface while being kept parallel to the chassis withoutchange in the tape running direction, the above problems would notoccur. In practice, however, because the cylinder is inclined withrespect to the chassis surface and the magnetic tape must be helicallywound round the cylinder so as to lie higher on the upstream side andlower on the downstream side under a loaded condition, the magnetic tapeis in contact with the cylinder and the attitude thereof is also changedduring the tape loading process, thereby producing the above problems.

In order to restrain such change in the attitude of the magnetic tapeduring the tape loading process, this embodiment is constituted suchthat the passages of the guide rollers 10 and 8 on the upstream side (aswell as on the downstream side) are set separately from each other.Thus, the tape loading process is divided into a plurality of steps eachof which represent a divided location. Then, the shift amount of thetape level is derived by loading simulation (tape attitude analysisprogram) for each of the divided locations, thereby allowing thepassages of the guide bases 36 and 37 in the guide plate 22 as well asthe motional relationship between the guide bases 35 and 36, and theguide bases 37 and 38 to be determined so that each of the shift amountsof the tape level for the respective divided locations become minimum.Incidentally, the guide bases 35 and 38 are moved parallel to thechassis surface.

FIG. 5 shows thus-determined withdrawn conditions of the magnetic tapeat the respective divided locations during the loading process.

In FIG. 5, conditions of the magnetic tape 12 withdrawn out of the tapecassette 44 according to the movement of the guide rollers 8 and 9, andthe guide rollers 10 and 11 are represented in order of the dividedlocations a, b, . . . , i. Here, the location a represents an unloadedcondition where the guide rollers 8 and 9, and the guide rollers 10 and11 are positioned in the opening of the cassette tape 44 inside of themagnetic tape 12. The locations b-d represent conditions of the magnetictape 12 before and after it has been withdrawn out of the tape cassette44 and comes into contact with the cylinder 6. The locations e-grepresent conditions of the magnetic tape 12 before and after theupstream guide bases 36 and 37 reach slopes of the first tilt surfaces 2and 4 of the cylinder bases 1, respectively.

FIG. 6 shows the tape loading process of FIG. 5 in three dimensionsbased on CAD.

FIG. 7 illustrates the shift amounts of the tape level at the respectivelocations a, b, c, . . . , i in FIG. 5 under conditions that theconfigurations of the tilt surfaces 2, 3, 4 and 5 of the cylinder base 1as well as the motional relationship between the guide rollers 10 and11, and the guide rollers 8 and 9 are set optimum for the attitude ofthe magnetic tape. The result of FIG. 7 was derived by computersimulation. In FIG. 7, the X direction coincides with the lengthwisedirection of the magnetic tape extending from the supply reel 46 to thetake-up reel 47, and the Z direction coincides with the shift directionof the tape level. The result of computer simulation is as follows.Specifically, at the locations a-c before the magnetic tape 12 startscontacting with the cylinder 6, the shift amounts of the tape level aresubstantially zero. After that, there occurs a shift of the tape level.As shown in FIG. 7, however, the maximum shift amounts of the tape levelin the positive and negative directions are +1.05 mm (the location i)and - 0.99 mm (the location h), respectively. In other words, the shiftamounts of the tape level throughout the tape loading process are heldless than ±1 mm. This value is greatly improved as compared with thevalue of ±6 mm in the prior art.

In this embodiment, the guide rollers 10 and 11 moving on the outer sideare arranged to move parallel to the chassis surface. But, these guiderollers 10 and 11 may be three-dimensionally arranged in such a manneras to move upwardly and downwardly, respectively, as the guide rollers 8and 9 do. With such arrangement, while the guide plate and the tiltsurfaces of the cylinder base are complicated in their configuration,the degree of freedom in surface configuration of the respective tiltparts is increased. Also, the shift amount of the tape level is furtherimproved. Note that in this case, it is preferable to move the guiderollers 10 and 11 movable on the outer side ahead of the guide rollers 8and 9 movable on the inner side.

Although the above-described embodiment is arranged as providing oneguide roller on each guide base, it is also possible that two guiderollers are provided on each guide base, or that a fixed guide isprovided in combination with the guide roller.

In the arrangement where the tilt guide having a small tilt angle isdisposed nearest to the cylinder, for example, the running direction ofthe magnetic tape is changed in the nearest vicinity of the cylinder sothat the attitude of the magnetic tape is changed with respect to themagnetic head provided on the rotatable cylinder. This is advantageousto optimally adjust a so-called touch or contact state between themagnetic head and the magnetic tape.

Next, a drive mechanism of the pinch roller will be described. FIGS. 1to 3, the element designated at a reference numeral 142 is a plate; 140is a worm; 70 is a bearing; 41 is a drive lever; and 141 is a geartrain.

In FIGS. 1 to 3, the plate 142 is provided with a shaft erected thereon,and the worm wheel 42 is mounted on that shaft through a bearing 70.Accordingly, the worm wheel 42 is rotatable about that shaft. The pinchroller arm 40 is mounted to the bearing 70. The drive lever is plantedon the worm wheel 42 and has its distal end coupled to the pinch rollerarm 40. This causes the pinch roller arm 40 and the worm wheel 42 torotate together. The pinch roller 19 formed of neoprene rubber or thelike is rotatably born at the distal end of the pinch roller arm 40through a bearing. This bearing has the automatic centering structurewhere the center shaft of the pinch roller 19 is supported by a singleball bearing. The worm wheel 42 is coupled to the pinch roller drivemotor 43 through the gear train 141 and the worm 140.

When the pinch roller arm 40 is at such a state as shown in FIG. 1 underan unloaded condition, the loading operation is started and the pinchroller drive motor 43 subsequently is actuated, causing the pinch rollerarm 40 to be swung clockwise about the bearing 70. Under a loadedcondition, as shown in FIG. 2, the self-lock function between the worm140 and the worm wheel 42 continuously produces a press force forpressing the pinch roller 19 against the capstan 20, even after thepinch roller drive motor 43 is deenergized.

The above pinch roller drive mechanism can present the followingadvantages:

(1) The accurate and appropriate press force for pressing the pinchroller 19 against the capstan 20 is easily obtained by controlling thedrive voltage applied to the pinch roller drive motor;

(2) No solenoid is required and power consumption is hence saved. Also,the peak current becomes lower. Therefore, even when power isinterrupted for some abnormal event while the pinch roller is kept in apressure contact state, in particular, the pinch roller drive motor canbe energized through discharge of a capacitor of small capacitance sothat the pinch roller is easily released from its pressure contact statewith the capstan. This prevents such drawbacks as deformation of thepinch roller and slack of the magnetic tape; and

(3) Since the pinch roller drive system is independent from the loadingsystem, the load of the loading motor is alleviated and the loading timeis shortened.

FIG. 14 shows a partial section of the construction of a reel basemechanism employed in FIGS. 1 to 3. FIG. 14 illustrates the structure onthe take-up up side by way of example. The supply side has the samestructure as the take-up side shown in FIG. 14 does. In the figure, theelement designated at a reference numeral 151 is a brake plate; 152 is abrake shoe; 153 is a spring; 154 is a rotation checking stopper; 155 isa coil, 156 is a rotatable shaft; and 157 is a reel motor.

In the reel base mechanism shown in FIG. 14, the reel base 48 isdirectly driven by the reel motor 157, and the brake plate 151concentric with the reel base 48 is used as a main brake (holder brake),thereby constituting a disk brake type mechanism which is adaptable forquick switching of mode and achievement of higher reliability.

More specifically, the reel motor 157 mounted to the lower surface ofthe chassis 7 has its rotatable shaft 156 projecting above the chassis7. The reel base 48 is press fitted over the upper end of the rotatableshaft 156. Between the reel base 48 and the chassis 7, there is disposedthe disk-like brake plate 151 facing the lower surface of the reel base48. The brake shoe 152 is annually fixed to the upper surface of thebrake plate 151 about the rotatable shaft 156. The brake plate 151 isbiased toward the reel base 48 by a spring 153 fitted around therotatable shaft 156. Further, the brake plate 151 is controlled by therotation checking stopper 154 in such a manner that it can be displacedin an axial direction with respect to the stationary part, but cannot berotated about the rotatable shaft 156. In addition, between the brakeplate 151 and the chassis 7, there is disposed the coil 155 about therotatable shaft 156.

When the coil 155 is not energized, the brake plate 151 is raised up bya biasing force of the spring 153 so that the brake shoe 152 is pressedagainst the lower surface of the reel base 48 to brake the reel base 48.When the coil 155 energized, there is produced is an electromagneticforce to attract the brake plate 151 toward the coil 155 against thebiasing force of the spring 153, whereby the brake shoe 151 isdisengaged from the lower surface of the reel base 48 to release thereel base 48.

Thus, during a tape running mode, the coil 155 is energized to releasethe brake, and the reel motor 157 is driven for rotating the reel base48. When the magnetic tape is to be stopped, the reel motor 157 isdeenergized and simultaneously the coil 155 is also deenergized. Thebrake is thereby applied at once.

FIGS. 13A and 13B show the tape tension detecting mechanism in FIG. 1.In the figures, the element designated at a reference numeral 69 is ashaft; 118 is a lever holder; 103 and 104 are gears; 116 is a holdergear; 111 and 113 are pins; 112 is a magnet; 102 is a torsion spring;114 and 115 are collars; 121, 122 and 134 are bearings; 117 is a holderplate; 132, 133 and 135 are spacers; 105 and 106 are center shafts; 107and 123 are screws; 110 is a tension pin; 124 is a stopper; 109 is agear retainer; 127 and 128 are guide shafts; 129 is a base plate; 126 isa sensor substrate; 130 is an adjusting screw; and 131 is a spring.

In FIGS. 13A and 13B, the tension plate 68 is provided with the shaft 69erected thereon, and the lever holder 118 is rotatably mounted on theshaft 69 through the bearings 121 and 122 in such manner that an innerrace of the bearing 122 is secured by the screw 123 through the spacer133. The tension lever 39 is fixed to the lever holder 118 by means ofscrews or the like. The tension pin 110 is press fitted into the tensionlever 39, and the tension roller 21 is rotateably mounted on the tensionpin 110 with the stopper 124 capped at the distal end of the tension pin110.

Meanwhile, the holder plate 117 which has the magnet 112 press fittedtherein and is formed with a slit 120, is rotatably fitted to the leverholder 118. The holder gear 116 which has the pin 113 press fittedtherein and is formed with slits 119 and 125 is rotatable with respectto the lever holder 118 through the bearing 134 and is positioned by thespacer 132. The level of the holder plate 117 is determined by thespacer 135. A gap is defined between the inner periphery of the spacer135 and the lever holder 118. The pin 111 is press fitted at its upperend into the lever holder 118, while it extends through a hole formed inthe holder plate 117 and is slideably fitted in the slit 119 of theholder gear 116. The tension lever 39 and the holder plate 117 are thusrotated together. The pin 113 is press fitted at its lower end into theholder gear 116, while it slidably extends through the groove hole 120of the holder plate 117. The collars 114 and 115 are rotatably fitted onthe pins 111 and 113, respectively. The torsion spring 102 is engagedbetween the collars 114 and 115. This arrangement of the torsion spring102 is shown in FIG. 13B. In case that the pin 113 is fixed, the tensionlever 39 is biased counterclockwise by the torsion spring 102. Theholder gear 116 is coupled to the loading ring 27 through the gears 103and 103. The gears 104 and 104 are rotatably mounted on the centershafts 105 and 106 both planted upright on the tension plate 68,respectively. The gear retainer 109 is secured by the screw 107 to ashaft 108 planted on the tension plate 68.

The sensor substrate 126 is disposed close to the lower surface of themagnet 112. Though not shown, the sensor substrate 126 includes two Hallelements, for example, which are arranged to be spaced in the movingdirection of the magnet 112 in opposite relation to the magnet 112. Inthis case, a rotational angle of the tension lever 39 is detected byusing a differential output between the Hall elements. The sensorsubstrate 126 is fixed to the base plate 129 by means of screws or thelike. The base plate 129 is slidable in the lengthwise direction of theslits and is adapted to be stopped by the guide shafts 127 and 128planted on the tension plate 68. The base plate 129 is positioned at itsone end by the adjusting screw 130 through the spring 131, which extendsloosely through a hole formed in the tension plate 68.

When the loading ring 27 is revolved clockwise upon start of the loadingoperation, the gear 103 and the holder gear 116 start rotatingcounterclockwise, and the gear 104 starts rotating clockwise. Thetension level 39 is therefore rotated counterclockwise together with theholder gear 116 and the holder plate 117. As shown in FIG. 1, however,since the distal end of the tension lever 39 is held in abutment withthe guide base 35, the tension lever 39 is little moved until the guidebase 35 is moved to a certain extent in the loading direction.Accordingly, the holder plate 117, the magnet 112, the pin 111 and theslit 120 which are movable together with the tension lever 39 are alsonot moved until the guide base 35 is moved to a certain extent. But, theholder gear 116 and the slit 125 and 119 formed thereon, as well as thepin 113 are rotated counterclockwise during such a period. The torsionspring 102 is thus compressed to reduce its mount angle corresponding toan angular space between the pins 111 and 113, and this producesreaction tending to move the tension lever 39 counterclockwise. Thisreaction is very small as compared with the force applied to move theguide base 35. Further, at the start of the loading operation, thetiming at which the tension lever 39 is rotated counterclockwise isdelayed from the timing at which the loading ring 27 and the guide base35 start moving. During the unloading operation, in order to prevent theguide base 35 and the tension lever 39 from meshing with each other, asthe guide base 35 is moved in the unloading direction, the tension lever39 is pushed by the guide base 35 upon encountering the guide base 35,so that the tension lever 39 is then rotated clockwise for being putback into the tape cassette. The tension lever 39 is assembled in such amanner as to produce slight reaction under an unloaded condition. Thisslight reaction serves as a force for positioning the tension roller 21.

When the guide base 35 is moved beyond a certain extend, the distal endof the tension lever 39 is spaced from the side face of the guide base35. With the aforesaid reaction, the tension lever 39 is now rotatedcounterclockwise by the angle through which the torsion spring 102 hasbeen compressed. Under this condition, the relative positionalrelationship between the holder gear 116 and the holder plate 117returns back to be the same as that at the initial stage. Afterward, thetension lever 39 is rotated together with the holder gear 116 and theholder plate 117.

The condition where the loading operation has been completed is shown inFIG. 2. The tension roller 21 is brought into contact with the magnetictape 12, and the tension lever 39 is rotated by such an angle at whichthe tension of the magnetic tape 12 is balanced by the biasing force ofthe torsion spring 102. Accordingly, as the tape tension varies, therotational angle of the tension lever 39 is also varied. Also, theposition of the base plate 129 is adjusted beforehand by the adjustingscrew 131 such that the magnet 112 is positioned opposite to the Hallelements on the sensor substrate 126 under the above balanced condition.On the other hand, the rotational position of the holder gear 116 isheld stationary at a point corresponding to the position whererevolution of the loading ring 27 has been terminated.

Incidentally, the collars 114 and 115 serve to prevent the occurrence ofan excessive frictional force between the tension lever 39 and theholder gear 116, and hence reduction in the detection accuracy, at thetime when the tape tension is detected.

As described above, the following advantageous effects can be obtainedwith the present invention:

(1) The running path of the magnetic tape is prevented in its directionfrom being abruptly changed in the widthwise direction of the magnetictape;

(2) The attitude of the magnetic tape is kept steadily during the tapeloading process, so that the magnetic tape is protected from damage andstable tape running is achieved.

(3) Since the pinch roller lever is driven independently of the pinchroller drive motor, the load of the loading motor is alleviated and theloading time is shortened. Further, large power is not required to bringthe pinch roller into pressure contact with the capstan, enabling asavings in power consumption;

(4) Since the tilt surfaces necessary for the tape loading operation andthe tape running system are all integrally incorporated into thecylinder base, the attitude of the magnetic tape is high-accurately andstably held throughout the tape loading process and the tape runningprocess. The magnetic tape is thus protected from damage; and

(5) Since the mechanism for detecting the tape tension is provided andcooperated with operation of the tape loading mechanism, it becomespossible to easily achieve higher accuracy of the running performance ofthe magnetic tape and more advanced function of VCRs. This furthercontributes to protect the magnetic tape from damage.

The present invention can be practiced in other forms than disclosed inthe foregoing embodiment without departing from the spirit and principalfeatures of the invention. Accordingly, the foregoing embodiment ismerely one illustrated example of the present invention in all respectsand should not be construed in any limiting sense. The scope of thepresent invention is defined in attached claims. Modifications andchanges which can be made within the range equivalent to the scope ofthe claims are all included in the scope of the present invention.

What is claimed is:
 1. A tape loading mechanism for a VCR of the helicalscan type in which a magnetic tape is withdrawn out of a tape cassetteand wound round the outer peripheral surface of a rotatable cylindermounted on a cylinder base, said mechanism comprising:a plurality ofmovable tape guide members reciprocable independently and separatelyfrom each other between a first position near said tape cassette and asecond position located around the outer peripheral surface of saidrotatable cylinder and more remote from said tape cassette than saidfirst position, all of or a plural number of said movable members beingon a tape running upstream side or a tape running downstream side withrespect to said rotatable cylinder around at least the outer peripheralsurface of said rotatable cylinder, said all of or plural number of saidmovable members being movable along the outer periphery of saidrotatable cylinder at respective positions offset from each other in theoutward radial direction of said rotatable cylinder, said movablemembers each comprising a first movable portion which comes into contactwith a face of said magnetic tape, and a second movable portionconnected to said first movable portion for supporting said firstmovable portion, and said magnetic tape being contacted with saidmovable members and thereby withdrawn out of said tape cassette whensaid movable members are operated to move from said first positiontoward said second position, and said magnetic tape being put back intosaid tape cassette when said movable members are operated to move fromsaid second position toward said first position; and guide passageforming means, said guide passage forming means being fixed to astationary component side of said mechanism to be arranged along theouter peripheral surface of said rotatable cylinder, and having suchsize and configuration as to allow connection of said first position andsaid second position with each other, for forming guide passages alongwhich said movable members are moved round the outer peripheral surfaceof said rotatable cylinder, said guide passage forming means including:a plurality of guide portions formed independently of each other betweensaid first position and said second position along respective movementpaths along which respective ones of said movable members are movedbetween said first position and said second position, each of saidplurality of guide portions being engaged with respective ones of saidsecond movable portions of said plurality of movable members and whereinsaid tape loading mechanism includes stationary tilt guide members fixedto the stationary component side of said mechanism, said stationary tiltguide members each having its surface brought into contact with saidmagnetic tape withdrawn out of said tape cassette by said movablemembers for converting the attitude and the running direction of saidmagnetic tape, and said stationary tilt guide members each being locatedbetween respective ones of said plurality of movable members on the taperunning path under a condition that said movable members have been movedto at least said second position, wherein said plurality of movable tapeguide members are arranged such that said movable members are disposedin plural number independently and separately from each other for eachof the tape running upstream side and the tape running downstream sidewith respect to said rotatable cylinder respectively around oppositesides of the outer peripheral surface of said rotatable cylinder; andsaid guide passage forming means is arranged such that in associationwith said tape guide members, said guide portions are formed in pluralnumber independently and separately from each other for each of the taperunning upstream side and the tape running downstream side with respectto said rotatable cylinder respectively around the opposite sides of theouter peripheral surface of said rotatable cylinder, and wherein saidguide passage forming means includes on each of the tape runningupstream side and the tape running downstream side at least one guideportion comprising a first rectilinear plane portion which extendsbetween said first position and said second position and has a firsttilt angle tilted in the direction from said first position toward saidsecond position with the plane of said tape cassette as a reference, anda second rectilinear plane portion which has a second tilt angle whichis similar to a tilt angle of one of said stationary tilt guide membersof the mechanism.
 2. A tape loading mechanism for a VCR according toclaim 1, wherein said second tilt angle is larger than said first tiltangle.
 3. A tape loading mechanism for a VCR according to claim 2,wherein said first rectilinear plane portion and said second rectilinearplane portion are tilted in the same direction.
 4. A tape loadingmechanism for a VCR according to claim 1, wherein said first rectilinearplane portion and said second rectilinear plane portion are tilted inthe same direction.
 5. A tape loading mechanism for a VCR of the helicalscan type in which a magnetic tape is withdrawn out of a tape cassetteand wound round the outer peripheral surface of a rotatable cylindermounted on a cylinder base, said mechanism comprising:a plurality ofmovable tape guide members reciprocable independently and separatelyfrom each other between a first position near said tape cassette and asecond position located around the outer peripheral surface of saidrotatable cylinder and more remote from said tape cassette than saidfirst position, all of or a plural number of said movable members beingon a tape running upstream side or a tape running downstream side withrespect to said rotatable cylinder around at least the outer peripheralsurface of said rotatable cylinder, said all of or plural number of saidmovable members being movable along the outer periphery of saidrotatable cylinder at respective positions offset from each other in theoutward radial direction of said rotatable cylinder, said movablemembers each comprising a first movable portion which comes into contactwith a face of said magnetic tape, and a second movable portionconnected to said first movable portion for supporting said firstmovable portion, and said magnetic tape being contacted with saidmovable members and thereby withdrawn out of said tape cassette whensaid movable members are operated to move from said first positiontoward said second position, and said magnetic tape being put back intosaid tape cassette when said movable members are operated to move fromsaid second position toward said first position; and guide passageforming means, said guide passage forming means being fixed to astationary component side of said mechanism to be arranged along theouter peripheral surface of said rotatable cylinder, and having suchsize and configuration as to allow connection of said first position andsaid second position with each other, for forming guide passages alongwhich said movable members are moved round the outer peripheral surfaceof said rotatable cylinder, said guide passage forming means a includinga plurality of guide portions formed independently of each other betweensaid first position and said second position along respective movementpaths along which respective ones of said movable members are movedbetween said first position and said second position, each of saidplurality of guide portions being engaged with respective ones of saidsecond movable portions of said plurality of movable members and whereinsaid tape loading mechanism includes stationary tilt guide members fixedto the stationary component side of said mechanism, said stationary tiltguide members each having its surface brought into contact with saidmagnetic tape withdrawn out of said tape cassette by said movablemembers for converting the attitude and the running direction of saidmagnetic tape, and said stationary tilt guide members each being locatedbetween respective ones of said plurality of movable members on the taperunning path under a condition that said movable members have been movedto at least said second position, wherein said plurality of movable tapeguide members are arranged such that said movable members are disposedin plural number independently and separately from each other for eachof the tape running upstream side and the tape running downstream sidewith respect to said rotatable cylinder respectively around oppositesides of the outer peripheral surface of said rotatable cylinder; andsaid guide passage forming means is arranged such that in associationwith said tape guide members, said guide portions are formed in pluralnumber independently and separately from each other for the tape runningupstream side and/or the tape running downstream side with respect tosaid rotatable cylinder respectively around the opposite sides of theouter peripheral surface of said rotatable cylinder, and wherein saidguide passage forming means is arranged such that a first guide portionand a second guide portion are tilted in the moving direction of saidtape guide members from said first position toward said second positionwith the plane of said tape cassette being as a reference, and have tiltangles larger than those of a third guide portion and a fourth guideportion which are disposed more remote from the outer peripheral surfaceof said rotatable cylinder than said first guide portion and said secondguide portion, respectively, wherein said movable tape guide members arearranged such that on both the tape running upstream side and the taperunning downstream side with respect to said rotatable cylinder, theouter movable members disposed more remote from the outer peripheralsurface of said rotatable cylinder are operated to move from said firstposition toward said second position ahead of the inner movable membersdisposed nearer to the outer peripheral surfaced of said rotatablecylinder, respectively.
 6. A tape loading mechanism for a VCR of thehelical scan type in which a magnetic tape is withdrawn out of a tapecassette and wound round the outer peripheral surface of a rotatablecylinder mounted on a cylinder base, said mechanism comprising:aplurality of movable tape guide members reciprocatable independently andseparately from each other between a first position near said tapecassette and a second position located around the outer peripheralsurface of said rotatable cylinder and more remote from said tapecassette than said first position, said movable members each having afirst movable portion coming into contact with the face of said magnetictape, and a second movable portion connected to said first movableportion for supporting said first movable portion, and stationary tiltguide members fixed to said cylinder base, said stationary tilt guidemembers being located along with said movable members in the taperunning path around the outer peripheral surface of said rotatablecylinder, and each having its surface brought into contact with saidmagnetic tape withdrawn out of said tape cassette by said movablemembers for converting the attitude and the running direction of saidmagnetic tape, said magnetic tape being contacted with said movablemembers and thereby withdrawn out of said tape cassette when saidmovable members are operated to move from said first position towardsaid second position, and said magnetic tape being put back into saidtape cassette when said movable members are operated to move from saidsecond position toward said first position; and guide passage formingmeans, said guide passage forming means being fixed to a stationarycomponent side of said mechanism to be arranged along the outerperipheral surface of said rotatable cylinder, and having such size andconfiguration as to allow connection of said first position and saidsecond position with each other, for forming guide passages along whichsaid movable members are moved between said first position and saidsecond position, said guide passage forming means including a pluralityof guide portions independently of each other between said firstposition and said second position along respective movement paths alongwhich respective ones of said movable members are moved between saidfirst position and said second position, each of said plurality of guideportions being engaged with respective ones of said second movableportions of said plurality of movable members, and wherein said tapeloading mechanism is arranged such that said movable members aredisposed in plural number independently and separately from each otherfor each of the tape running upstream side and the tape runningdownstream side with respect to said rotatable cylinder respectivelyaround opposite sides of the outer peripheral surface of said rotatablecylinder, and wherein said guide passage forming means is arranged suchthat in association with said movable tape guide members, said guideportions are formed in plural number independently and separately fromeach other for each of the tape running upstream side and the taperunning downstream side with respect to said rotatable cylinderrespectively around opposite sides of the outer peripheral surface ofsaid rotatable cylinder, and wherein said guide passage forming means isarranged such that a first guide portion and a second guide portion aretilted in the moving direction of said tape guide members from saidfirst position toward said second position with the plane of said tapecassette being as a reference, and have tilt angles larger than those ofa third guide portion and a fourth guide portion which are disposed moreremote from the outer peripheral surface of said rotatable cylinder thansaid first guide portion and said second guide portion, respectively,wherein said tape guide members are arranged such that on both the taperunning upstream side and the tape running downstream side with respectto said rotatable cylinder, the outer movable members disposed moreremote from the outer peripheral surface of said rotatable cylinder areoperated to move from said first position toward said second positionahead of the inner movable members disposed nearer to the outerperipheral surface of said rotatable cylinder, respectively.